Bend mesh without deforming the whole body

I am trying to bend the arms up above the head of a mesh reference of a man (1.3 MB)

Hello - that will be pretty tough, I would say, to pull off with any kind of natural effect, in Rhino. I think @DanielPiker has been looking at some ways to rig a skeleton in a mesh, (maybe?) for just this type if thing. Do I have that right, Daniel?